This chapter describes the modules (mods) included in the Oracle HTTP Server. The modules extend the basic functionality of the Web server, and support integration between Oracle HTTP Server and other Oracle Database components.

Documentation from the Apache Software Foundation is referenced when applicable.

Note:

Readers using this guide in PDF or hard copy formats will be unable to access third-party documentation, which Oracle provides in HTML format only. To access the third-party documentation referenced in this guide, use the HTML version of this guide and click the hyperlinks.

List of Modules

Table 7-1 lists all the Oracle HTTP Server modules discussed in this chapter.

mod_autoindex

mod_cern_meta

Emulates CERN (Conseil Europeen pour le Recherche Nucleaire) HTTPD metafile semantics. Metafiles are additional HTTP headers that can be produced for each file the server accesses, in addition to the typical set.

This module is not supported by Oracle.

mod_certheaders

Enables reverse proxies that terminate SSL connections in front of Oracle HTTP Server to transfer information regarding SSL connection, such as SSL client certificate information, to Oracle HTTP Server, and applications running behind Oracle HTTP Server. This information is transferred from the reverse proxy to Oracle HTTP Server using HTTP headers. The information is transferred from the headers to the standard CGI environment variable, which mod_ossl or mod_ssl populates if the SSL connection is terminated by Oracle HTTP Server. It also enables certain requests to be treated as HTTPS requests even though they are received through HTTP.

Specify which headers should be translated to CGI environment variables. This can be achieved by using the AddCertHeader directive. This directive takes a single argument, which is the CGI environment variable that should be populated from a HTTP header on incoming requests. For example, to populate the SSL_CLIENT_CERT CGI environment variable, add the following line to httpd.conf:

AddCertHeader SSL_CLIENT_CERT

The AddCertHeader directive can be a global setting if it is placed in the base virtual server section of httpd.conf. It can be specific to a single virtual host by placing it within a virtual host container, or it can be specific to a set of URIs by placing it within a <Directory> or <Location> container directive within httpd.conf. The combination of these directives are additive, so that for a given URI, all directives that are specific to that URI will be added to any that are specific to that request's virtual host, which will be added to any that is defined for that base virtual host.

mod_certheaders can be used to instruct Oracle HTTP Server to treat certain requests as if they were received through HTTPS even though they were received through HTTP. This is useful when Oracle HTTP Server is front-ended by a reverse proxy or load balancer, which acts as a termination point for SSL requests, and forwards the requests to Oracle HTTP Server through HTTPS.

For load balancers, mod_certheaders must be explicitly configured to determine which requests should be treated as HTTPS requests. To do this, use the following directive:

mod_cgi

mod_define

Enables the Define directive, which defines a variable that can be expanded on any configuration line. The Define directive has the status Extension, which means that it is not compiled into the server by default.

mod_dir

Enables the server to perform slash (/) redirects. Directories must contain a trailing slash. If a request for a URL without a trailing slash is received, mod_dir redirects the request to the same URL followed by a trailing slash. For example:

mod_example

Provides examples and guidance on how to write modules using the Apache API. When implemented, it demonstrates module callbacks triggered by the server.

This module is not supported by Oracle.

mod_expires

Enables the server to generate Expires HTTP headers, which provide information to the client about document validity. Documents are served from the source if, based on the expiration criteria, the cached copy has expired.

mod_mime

mod_mime_magic

Enables the server to determine the MIME type of a file by examining a few bytes of its content. It is used in cases when mod_mime cannot determine a file type. Make sure that mod_mime appears before mod_mime_magic in the configuration file, so that mod_mime processes the files first.

mod_negotiation

mod_onsint

This module provides integration support with Oracle Notification Service (ONS) and OPMN (Oracle Process Manager and Notification Server).

Benefits of mod_onsint

mod_onsint provides the following functionality:

Provides a subscription mechanism for ONS notifications within Oracle HTTP Server. This is particularly important on UNIX where Oracle HTTP Server employs a multi-process architecture. In such an architecture, it is not feasible to have an ONS subscriber in each process since there are up to 8192 processes that comprise a single Oracle HTTP Server instance. Instead, mod_onsint provides a single process that receives notification for all modules within an Oracle HTTP Server instance.

Publishes PROC_READY ONS notifications so that other components such as OPMN are notified that the listener is up and ready. It also provides information such as DMS metrics and information about how the listener can be contacted. These notifications are sent periodically by mod_onsint as long as the Oracle HTTP Server instance is running.

Provides functionality that enables Oracle HTTP Server to terminate as a single unit if the parent process fails. The parent process is responsible for starting and stopping all of the child processes for an Oracle HTTP Server instance. The failure of the parent process without first shutting down the child processes leaves Oracle HTTP Server in an inconsistent state that can only be fixed by manually killing all of the orphaned child processes. Until this is done, a new Oracle HTTP Server instance cannot be started since the orphaned child processes still occupy the ports Oracle HTTP Server wants to use. mod_onsint provides a monitor of the parent process. If it detects that the parent process has died, it kills all of the remaining child processes. When combined with OPMN, this provides restartability for Oracle HTTP Server in the case of a parent process failure. mod_onsint ensures that all of the Oracle HTTP Server child processes die, leaving the ports open for a new Oracle HTTP Server instance. OPMN ensures that a new instance is started once the failure of the original instance is detected.

Implementation Differences for mod_onsint

Due to the difference in architecture of Oracle HTTP Server on UNIX and Windows, the implementation of mod_onsint varies slightly on these platforms.

On UNIX, mod_onsint spawns a process at module initialization time. This process is responsible for watching the parent process as well as sending and receiving ONS messages. Callback functions from other modules interested in ONS notifications are made in this process. For this information to be shared with other Oracle HTTP Server child processes, the use of an interprocess communication method such as a memory mapped file must be used. If a failure of a parent process is detected on UNIX, a signal is sent to all the other child processes, causing them to shut down.

On Windows, Oracle HTTP Server consists of only two processes, the parent and a multi-threaded child that handles all of the HTTP requests. In this model, mod_onsint runs as a thread within the child process. This thread watches the parent process as well as sending and receiving ONS messages. Callback functions from other modules interested in ONS notifications are made in the child process. If a failure of the parent process is detected, the mod_onsint terminates the child process, effectively shutting down Oracle HTTP Server.

There is no configuration of mod_onsint needed to provide functionality equivalent to that provided with Oracle HTTP Server in Oracle9i Application Server, Release 2 (9.0.2), other than the loading of the module. There is only an optional directive called OpmnHostPort that can be set. This directive enables you to specify a hostname and port that OPMN should use for pinging the Oracle HTTP Server instance that mod_onsint is running in. If OpmnHostPort is not specified, mod_onsint chooses an HTTP port automatically. However, in certain circumstances, you may want to choose a specific HTTP port and hostname that OPMN should use to ping the listener with.

OpmnHostPort takes a single argument which is a host:port string that specifies the values to pass to OPMN. For example, the following line would specify that OPMN should use the localhost interface and port 7778 to ping this listener:

OpmnHostPort localhost: 7778

This directive must be in the global section of the httpd.conf file. It cannot be embedded into any virtual host of location container. After installation, an OpmnHostPort directive is located in dms.conf. It points OPMN to the Oracle HTTP Server "diagnostic port", which is a special localhost only virtual host.

You cannot combine directives using the one-argument syntax with directives using the two-argument syntax. If you use the two-argument syntax, the default for groups without a group-specific secret key is 'disabled'.

mod_ossl

This Oracle module enables strong cryptography for Oracle HTTP Server. It is a plug-in to Oracle HTTP Server that enables the server to use SSL. It is very similar to the OpenSSL module, mod_ssl. However, in contrast to the OpenSSL module, mod_ossl is based on the Oracle implementation of SSL, which supports SSL, version 3, and is based on Certicom and RSA Security technology.

Database Usage Notes

This section provides information for mod_perl users working with databases. It explains how to test a local database connection and set character forms.

Using Perl to Access the Database

The following section contains information about using Perl to access the database. Perl scripts access databases using the DBI/DBD driver for Oracle. The DBI/DBD driver is part of Oracle Database. It calls Oracle Callable Interface (OCI) to access the databases.

DBI must be enabled in httpd.conf for DBI to function. To do this, perform the following steps:

If the script specifies "use Apache::DBI" instead of "use DBI", then it will only be able to run from http://<hostname.domain>:<port>/perl/<scriptname>.

Testing Database Connection

The following is a sample Perl script for testing the database connection of a local seed database. To use the script to test another database connection, you must replace scott/tiger with the user name and password for the target database.

Using SQL NCHAR Datatypes

SQLNCHAR datatypes have been refined in Oracle9i, and are now called reliable Unicode datatypes. SQLNCHAR datatypes such as NCHAR, NVARCHAR2 and NCLOB allow you to store any Unicode characters regardless of the database character set. The character set for those datatypes is specified by the national character set, which is either AL16UTF-16 or UTF8.

See Also:

Oracle9i documentation for more about SQLNCHAR datatypes.

This release of DBD::Oracle supports SQLNCHAR datatypes and provides driver extension functions to specify the character form for data binding. The following script shows an example to access SQLNCHAR data:

Example 7-3 Sample Script to Access SQLNCHAR Data

# declare to use the constants for character forms
use DBD::Oracle qw(:ora_forms);
# connect to the database and get the database handle
$dbh = DBI->connect( ... );
# prepare the statement and get the statement handle
$sth = $dbh->prepare( 'SELECT * FROM TABLE_N WHERE NCOL1 = :nchar1' );
# bind the parameter of a NCHAR type
$sth->bind_param( ':nchar1', $param_1 );
# set the character form to NCHAR
$sth->func( { ':nchar1' => ORA_NCHAR } , 'set_form' );
$sth->execute;

As shown in Example 7-3, the set_form function is provided as a private function that you can invoke with the standard DBI func() method. It takes an anonymous hash that specifies which placeholder should be associated with which character form. The valid values of character form are either ORA_IMPLICIT or ORA_NCHAR. Setting the character form to ORA_IMPLICIT causes the application's bound data to be converted to the database character set, and ORA_NCHAR to the national character set. The default form is ORA_IMPLICIT.

Another function is provided to specify the default character set form as follows:

# specify the default form to be NCHAR
$dbh->func( ORA_NCHAR, 'set_default_form' );

After this call is made, the form of all parameters is ORA_NCHAR, unless otherwise specified with set_form calls. Note that unlike the set_form function, this is a function on the database handle, so every statement from the database handle with its default form specified has the form of your choice by default.

set_form

This function sets the character form for parameter(s). Valid forms are either ORA_IMPLICIT (default) or ORA_NCHAR. The constants are available as: ora_forms in DBD::Oracle.

Example 7-4 Sample for set_form

# a declaration example for the constants ORA_IMPLICIT and ORA_NCHAR
use DBD::Oracle qw(:ora_forms);
# set the character form for the placeholder :nchar1 to NCHAR
$sth->func( { ':nchar1' => ORA_NCHAR } , 'set_form' );
# set the character form using the positional index
$sth->func( { 2 => ORA_NCHAR } , 'set_form' );
# set the character form for multiple placeholders at once
$sth->func( { 1 => ORA_NCHAR, 2 => ORA_NCHAR } , 'set_form' );

set_default_form

This function sets the default character form for a database handle.

Example 7-5 Default Character Form for a Database Handle

This Oracle module connects the Oracle HTTP Server to an Oracle database, enabling you to create Web applications using Oracle stored procedures.

In order to access a Web-enabled PL/SQL application, configure a PL/SQL Database Access Descriptor (DAD) for mod_plsql. A DAD is a set of values that specifies how mod_plsql connects to a database server to fulfill an HTTP request. Besides the connect details, a DAD contains important configuration parameters for various operations in the database and for mod_plsql in general. Any Web-enabled PL/SQL application which makes use of the PL/SQL Web ToolKit needs to create a DAD to invoke the application.

Any PL/SQL Application written using the PL/SQL Web ToolKit

Oracle Application Server Portal

Creating a DAD

The Oracle HTTP Server <Location> directive which defines a virtual path used to access the PL/SQL Web Application. This directive begins enclosing a group of directives that apply to the named Location.

For example, the directive <Location /myapp> defines a virtual path called "/myapp" that will be used to invoke a PL/SQL Web Application through a URL like http://host:port/myapp/.

Note:

Older versions of mod_plsql were always mounted on a virtual path with a prefix of '/pls'. This restriction is removed in newer versions but might still be a restriction imposed by some of the older PL/SQL applications.

The Oracle HTTP Server "SetHandler" directive which directs Oracle HTTP Server to enable mod_plsql to handle the request for the virtual path defined by the named Location

SetHandler pls_handler

Additional Oracle HTTP Server directives that are allowed in the context of a <Location> directive. Typically, the following directives are used:

Configuration Files

plsql.conf

This file contains the LoadModule directive to load mod_plsql into Oracle HTTP Server, any global setting for mod_plsql, and include directives for dads.conf and cache.conf. This file is included by the Oracle HTTP Server configuration file ORACLE_HOME/Apache/Apache/conf/oracle_apache.conf on UNIX or ORACLE_HOME\Apache\Apache\conf\oracle_apache.conf on Windows, which itself gets included in the primary Oracle HTTP Server configuration file httpd.conf.

dads.conf

This file contains the configuration parameters for the PL/SQLdatabase access descriptor (DAD). A DAD is a set of values that specifies how mod_plsql connects to a database server to fulfill a HTTP request.

cache.conf

This file contains the configuration settings for the file system caching functionality implemented in mod_plsql. This configuration file is relevant only if PL/SQL applications use the OWA_CACHE package to cache dynamically generated content in the file system.

Configuration Parameters

Table 7-3 contains a list of mod_plsql configuration parameters. They are discussed in detail in later sections.

While specifying a value for a configuration parameter, follow Oracle HTTP Server conventions for specifying values. For instance, if a value has white spaces in it, enclose the value with double quotes. For example: PlsqlNLSLanguage "TRADITIONAL CHINESE_TAIWAN.UTF8"

Also, multi-line directives enables you to specify the same directive multiple times in a DAD.

PlsqlDMSEnable

PlsqlLogEnable

Debug level logging is meant to be used for debugging purposes only. When logging is enabled, log files are generated at:

UNIX: ORACLE_HOME/Apache/modplsql/logs

Windows: ORACLE_HOME\Apache\modplsql\logs

as configured by PlsqlLogDirectory. This parameter should be set to "Off" unless recommended by Oracle support to debug problems with mod_plsql.

To view more details about the internal processing of mod_plsql, set this directive to "On". This causes mod_plsql to start logging for every request that is processed. The log files are generated as specified by the PlsqlLogDirectory directive.

Category

Value

Syntax

PlsqlLogEnable On/Off

Default

Off

Example

PlsqlLogEnable Off

PlsqlLogDirectory

Specifies the directory where debug level logs are written out.

Set the directory name of the location where log files should be generated when logging is enabled. To avoid possible confusion about the location of this directory, an absolute path is recommended.

On UNIX, this directory must have write permissions by the owner of the child httpd processes.

Category

Value

Syntax

PlsqlLogDirectorydirectory

Default

None

Example

PlsqlLogDirectoryORACLE_HOME/Apache/modplsql/logs

PlsqlIdleSessionCleanupInterval

Specifies the time (in minutes) in which the idle database sessions should be closed and cleaned by mod_plsql.

This directive is used in conjunction with connection pooling of database connections and sessions in mod_plsql. When a session is not used for the specified amount of time, it is closed, and freed. This is done so that unused sessions can be cleaned, and the memory is freed on the database side.

Setting this time to a low number helps in faster cleanup of unused database sessions. Be aware that if this number is too low, then this may adversely affect the performance benefits of connection pooling in mod_plsql.

If the number of open database sessions is not a concern, you can increase the value of this parameter for best performance. In such a case, if the site is accessed frequently enough that the idle session cleanup interval is never reached for a session, then the DAD configuration parameter PlsqlMaxRequestsPerSession can be modified so that it is guaranteed that a pooled database session gets recycled on a regular basis.

For most installations, the default parameter value should suffice.

Category

Value

Syntax

PlsqlIdleSessionCleanupIntervalnumber

Default

15 (minutes)

Example

PlsqlIdleSessionCleanupInterval 15

dads.conf

This file contains the configuration parameters for the PL/SQL Database Access Descriptor (DAD).

DAD Parameters

This section describes all the DAD level parameters that can be specified in the dads.conf file. Besides these directives, you can also specify additional Oracle HTTP Server directives that can be specified in the context of a <Location> directive, such as:

Order deny,allow
AllowOverride None

The following parameters are discussed in detail in the subsequent sections:

PlsqlAfterProcedure

Specifies the procedure to be invoked after calling the requested procedure. This enables you to put a hook point after the requested procedure is called. This is useful in doing SQL*Traces/SQL Profiles while debugging a problem with the requested procedure. This is also useful when you want to ensure that a specific call be made after running every procedure.

Category

Value

Syntax

PlsqlAfterProcedurestring

Default

None

Example

PlsqlAfterProcedure portal.mypkg.myafterproc

Notes:

For all purposes, except for debugging, this parameter should be omitted. You could use this parameter to stop SQL Trace/SQL Profiling.

In older versions of the product, this parameter was called after_proc.

PlsqlAlwaysDescribeProcedure

Specifies whether mod_plsql should describe a procedure before trying to execute it. If this is set to "On", then mod_plsql will always describe a procedure before invoking it. Otherwise, mod_plsql will only describe a procedure when its internal heuristics have interpreted a parameter type incorrectly.

Category

Value

Syntax

PlsqlAlwaysDescribeProcedureOn/Off

Default

Off

Example

PlsqlAlwaysDescribeProcedure Off

Notes:

For all purposes, except for debugging, you should leave this parameter set to "Off".

In older versions of the product, this parameter was called always_desc.

PlsqlAuthenticationMode

Specifies the authentication mode to use for allow access through this DAD.

Most customer applications use Basic Authentication. Custom Authentication modes (GlobalOwa, CustomOwa, PerPackageOwa) are used by very few PL/SQL applications. The SingleSignOn mode is supported only for Oracle Application Server releases, and is used by Oracle Application Server Portal and Oracle Application Server Single Sign-On.

If the DAD is not using the Basic authentication, then you must include a valid username/password in the DAD configuration. For the Basic mode, if you wish to perform dynamic authentication, the DAD username/password parameters must be omitted.

In older versions of the product, this configuration parameter was derived from a combination of enablesso and custom_auth.

PlsqlBeforeProcedure

Specifies the procedure to be invoked before calling the requested procedure. This enables you to put a hook point before the requested procedure is called. This is useful in doing SQL*Traces/SQL Profiles while debugging a problem with the requested procedure. This is also useful when you want to ensure that a specific call be made before running every procedure.

Category

Value

Syntax

PlsqlBeforeProcedurestring

Default

None

Example

PlsqlBeforeProcedure portal.mypkg.mybeforeproc

Notes:

For all purposes, except for debugging purposes, this parameter should be omitted. You could use this parameter to start SQL Trace/SQL Profiling.

In older versions of the product, this parameter was called before_proc.

PlsqlBindBucketLengths

Specifies the rounding size to use while binding the number of elements in a collection bind. While executing PL/SQL statements, the Oracle database maintains a cache of PL/SQL statements in the shared SQL area, and attempts to reuse the cached statement if the same statement is executed again. Oracle's matching criteria requires that the statement texts be identical, and that the bind variable data types match. Unfortunately, the type match for strings is sensitive to the exact byte size specified, and for collection bindings is also sensitive to the number of elements in the collection. Since mod_plsql binds statements dynamically, the odds of hitting the shared cache are low, and it may fill up with near-duplicates and lead to contention for the latch on the shared area. This parameter reduces that effect by bucketing bind lengths to the nearest level.

All numbers specified should be in ascending order. After the last specified size, subsequent bucket sizes will be assumed to be twice the last one.

Category

Value

Syntax

PlsqlBindBucketLengthsnumber multiline

Default

4,20,100,400

Example

PlsqlBindBucketLengths 4

PlsqlBindBucketLengths 25

PlsqlBindBucketLengths 125

Notes:

This parameter is relevant only if you are using procedures with array parameters, and passing varying number of parameters to the procedure.

The default should be sufficient for most PL/SQL applications.

To see if this parameter needs to be changed, check the number of versions of a SQL statement in the SQL area.

Consider using flexible parameter passing to reduce the problem.

In older versions of the product, this parameter was called bind_bucket_lengths.

PlsqlBindBucketWidths

Specifies the rounding size to use while binding the number of elements in a collection bind. While executing PL/SQL statements, the Oracle database maintains a cache of PL/SQL statements in the shared SQL area, and attempts to reuse the cached statement if the same statement is executed again. Oracle's matching criteria requires that the statement texts be identical, and that the bind variable data types match. Unfortunately, the type match for strings is sensitive to the exact byte size specified, and for collection bindings is also sensitive to the number of elements in the collection. Since mod_plsql binds statements dynamically, the odds of hitting the shared cache are low, and it may fill up with near-duplicates and lead to contention for the latch on the shared area. This parameter reduces that effect by bucketing bind widths to the nearest level.

All numbers specified should be in ascending order. After the last specified size, subsequent bucket sizes will be assumed to be twice the last one.

The last bucket width must be equal to or less than 4000. This is due to the restriction imposed by OCI where array bind widths cannot be greater than 4000.

Category

Value

Syntax

PlsqlBindBucketWidthsnumber multiline

Default

32,128,1450,2048,4000

Example

PlsqlBindBucketWidths 40

PlsqlBindBucketWidths 400

PlsqlBindBucketWidths 2000

Notes:

This parameter is relevant only of you are using procedures with array parameters, and passing varying number of parameters to the procedure.

The default should be sufficient for most PL/SQL applications.

To see if this parameter needs to be changed, check the number of versions of a SQL statement in the SQL area.

Consider using flexible parameter passing to reduce the problem.

In older versions of the product, this parameter was called bind_bucket_widths.

PlsqlCGIEnvironmentList

Specifies overrides and/or additions of CGI environment variables to the default set of environment variables passed down to a PL/SQL procedure. This is a multi-line directive of name-value pairs to be added, overridden or removed. You can only specify one environment variable for each directive.

You can add CGI environment variables from the Oracle HTTP Server environment by specifying the variable name. To remove a CGI environment variable, set it equal to nothing. To add your own name-value pair, use the syntax myname=myvalue.

Category

Value

Syntax

PlsqlCGIEnvironmentList stringmultiline

Default

None

Example

To add a new environment variable from the Oracle HTTP Server environment:

PlsqlCGIEnvironmentList DOCUMENT_ROOT

To remove an environment variable:

PlsqlCGIEnvironmentList MYENVAR2=

To override from the Oracle HTTP Server environment:

PlsqlCGIEnvironmentList REQUEST_PROTOCOL=HTTPS

To add your own environment variable:

PlsqlCGIEnvironmentList MY_VARNAME=MY_VALUE

Notes:

Environment variables added here are available in the PL/SQL application through the function owa_util.get_cgi_env.

In older versions of the product, this parameter was called cgi_env_list.

PlsqlCompatibilityMode

Specifies the compatibility mode for running mod_plsql. This parameter is supported only for Oracle Application Server releases, and is used when you are using mod_plsql with an older version of Oracle Application Server Portal. In such situations, if you are running mod_plsql against a pre-9.0.2 version of Oracle Application Server Portal, this should be set to 1.

Category

Value

Syntax

PlsqlCompatibilityModeBitFlag

Default

0

Example

PlsqlCompatibilityMode 1

Notes:

This parameter enables an old bug in mod_plsql in which mod_plsql incorrectly converted the plus symbol (+) to space characters for document downloads. Enabling the first bit in this flag will make it impossible to download documents that have a plus symbol (+) in the document name.

PlsqlDatabaseConnectString

Specifies the connection to an Oracle database.

Category

Value

Syntax

PlsqlDatabaseConnectString

stringServiceNameFormat/SIDFormat/TNSFormat/NetServiceNameFormat, where string can be one of the following based on the second argument:

ServiceNameFormat: HOST:PORT:SERVICE_NAME format where HOST is the hostname running the database, PORT is the port number the TNS listener is listening on, SERVICE_NAME is the database service name.

SIDFormat: HOST:PORT:SID format where HOST is the hostname running the database, PORT is the port number the TNS listener is listening on, SID is the database SID.

TNSFormat: A valid TNS alias which resolves using Net8 utilities like tnsping and SQL*Plus.

NetServiceNameFormat: A valid net service name which resolves to a connect descriptor. A connect descriptor is a specially formatted description of the destination for a network connection. A connect descriptor contains destination service and network route information.

If the format argument is not specified, then mod_plsql assumes that `string' is either in the HOST:PORT:SID format, or resolvable by Net8. The differentiation between the two is made by the presence of the colon in the specified string.

It is recommended that newer DADs do not use the SIDFormat syntax. This exists only for backward compatibility reasons. Use the new two argument format for newly created DADs.

If the database is running in the same Oracle home, or the environment variable "TWO_TASK" is set (called "LOCAL" on Windows NT), this parameter need not be specified.

If the database is running in a separate Oracle home, then this parameter is mandatory.

If you have problems connecting to the database:

Check the username and password information in the DAD.

Make sure that you run "tnsping <string>" and execute commands such as:

sqlplus DADUsername/DADPassword@<string>

Ensure that TNS_ADMIN is configured properly.

Verify that the HOST:PORT:SERVICE_NAME format makes the connection go through.

Ensure that the TNS listener and database are up and running.

Ensure that you can ping the host from this machine.

From a mod_plsql perspective, TNSFormat and NetServiceNameFormat are synonymous and denote connect descriptors that are resolved by Net. The TNSFormat is provided as a convenience so that end-users use this to signify that the name resolution happens through the local tnsnames.ora. For situations where the resolution is through an LDAP lookup as configured in sqlnet.ora, it is recommended that the format specifier of NetServiceNameFormat be used.

If your database supports high availability, for example, RAC database, it is highly recommended that you use the NetServiceNameFormat such that the resolution for the net service name is through LDAP. This enables you to add or remove RAC nodes accessible through mod_plsql by just changing Oracle Internet Directory with the new/deleted node information. In such situations, hard-coding database listener HOST:PORT information in dads.conf or in the local tnsnames.ora is not recommended.

In older versions of the product, this configuration parameter was called connect_string.

PlsqlDatabasePassword

Specifies the password to use to log in to the database.

Category

Value

Syntax

PlsqlDatabasePasswordstring

Default

None

Example

PlsqlDatabasePassword tiger

After making manual configuration changes to DAD passwords, it is recommended that the DAD passwords are obfuscated by running the "dadTool.pl" script located in ORACLE_HOME/Apache/modplsql/conf.

Following are the steps to obfuscate DAD passwords:

If necessary, switch user to the Oracle software owner user, typically oracle using the following command:

$su - oracle

Set the ORACLE_HOME environment variable to specify the path to the Oracle home directory for the current release and set the PATH environment variable to include the directory containing the Perl executable and the location of the dadTool.pl script.

For example, to set the SHLIB_PATH environment in the Bourne shell on HP-UX systems, enter the following command:

$SHLIB_PATH=$ORACLE_HOME/lib:$SHLIB_PATH;export SHLIB_PATH

On Windows, include $ORACLE_HOME/bin in your PATH, for example:

set PATH=%ORACLE_HOME%\bin;%PATH%

Change directory to the mod_plsql configuration directory for the current release of Oracle HTTP Server:

cd $ORACLE_HOME/Apache/modplsql/conf

Invoke the following Perl script to obfuscate DAD password:

perl dadTool.pl -o

Notes:

This is a mandatory parameter, except for a DAD that sets PlsqlAuthenticationMode to Basic and uses dynamic authentication.

For DADs using SingleSignOn authentication, this parameter is the name of the schema owner.

In older versions of the product, this configuration parameter was called password.

PlsqlDatabaseUserName

Specifies the username to use to logon to the database.

Category

Value

Syntax

PlsqlDatabaseUsernamestring

Default

None

Example

PlsqlDatabaseUsername scott

Notes:

This is a mandatory parameter, except for a DAD that sets PlsqlAuthenticationMode to Basic and uses dynamic authentication.

For DADs using SingleSignOn authentication, this parameter is the name of the schema owner.

In older versions of the product, this configuration parameter was called username.

PlsqlDefaultPage

Specifies the default procedure to call if none is specified in the URL.

Category

Value

Syntax

PlsqlDefaultPagestring

Default

None

Example

PlsqlDefaultPage myschema.mypackage.home

Notes:

You can also use Oracle HTTP Server Rewrite rules to achieve the same effect as you get by setting this configuration parameter.

In older versions of the product, this parameter was called default_page.

PlsqlDocumentPath

Specifies a virtual path in the URL that initiates document download form the document table. For example, if this parameter is set to docs, then the following URLs will start the document downloading process for URLs of the format:

/pls/dad/docs
/pls/plsqlapp/docs

Category

Value

Syntax

PlsqlDocumentPath string

Default

docs

Example

PlsqlDocumentPath docs

Notes:

Omit this parameter for applications that do not perform document uploads or downloads.

In older versions of the product, this parameter was called document_table.

PlsqlErrorStyle

Specifies the Error Reporting Mode for mod_plsql errors. This parameter accepts the following values:

ApacheStyle: This is the default mode. In this mode, mod_plsql indicates to Oracle HTTP Server the HTTP error that was encountered. Oracle HTTP Server then generates the error page. This can be used with the Oracle HTTP Server ErrorDocument directive to produce customized error messages.

ModplsqlStyle: mod_plsql generates the error pages, usually a short message indicating the PL/SQL error that was encountered and PL/SQL exception stack, if any. For example:

scott.foo PROCEDURE NOT FOUND

DebugStyle: This mode provides more details than ModplsqlStyle. mod_plsql provides more details about the URL, parameters and also produces server configuration information. This mode is for debugging purposes only. Do not use this in a production system, since displaying internal server variables could be a security risk.

Category

Value

Syntax

PlsqlErrorStyle ApacheStyle/ModplsqlStyle/DebugStyle

Default

ApacheStyle

Example

PlsqlErrorStyle ModplsqlStyle

In older versions of the product, this parameter was called error_style.

PlsqlExclusionList

Specifies a pattern for excluding certain procedures, packages, or schema names from being directly executed from a browser. This is a multi-line directive in which each pattern occupies one line. The pattern is case-insensitive and can accept simple wildcards such as *, ? and [a-z]. The default patterns excluded from direct URL access are: sys.*, dbms_*, utl_*, owa_*, owa.*, htp.*, htf.*.

Setting this directive to "#NONE#" will disable all protection. This is not recommended for a live site, however, it is sometimes used for debugging purposes.

If this parameter is overridden, the defaults are no longer in effect. In that case, you must explicitly add the default list to the list of excluded patterns.

Besides the patterns specified with this parameter, mod_plsql also disallows any fully qualified procedure names which contain special characters like tabs, newlines, carriage-returns, single-quotes, the reverse slash, the form feed, the open parenthesis, close parenthesis, and space. This cannot be changed.

To add a pattern to the defaults, you must specify the default list with the pattern you have added (as in the example in the table).

In older versions of the product, this parameter was called exclusion_list.

PlsqlFetchBufferSize

Specifies the number of rows of content to fetch from the database for each trip, using either owa_util.get_page or owa_util.get_page_raw.

By default, mod_plsql attempts to fetch 200 response lines of output where each line is of 255 bytes. In situations where the response bytes are single-bytes, the response buffer is populated to the maximum and can pack 255*200=51000 bytes for each round trip. However, for responses containing multi-byte data, the byte packing for each row could be less than ideal resulting in lesser bytes getting transferred for each round trip. If your application generates large pages frequently and the response does not fit in one round trip, then consider setting this parameter higher. However, the memory usage for mod_plsql will increase.

Category

Value

Syntax

PlsqlFetchBufferSize number

Default

200

Example

PlsqlFetchBufferSize 256

Notes:

This parameter is changed only for performance reasons. The minimum value for this parameter is 28, but it is seldom reduced.

Change this parameter only under the following circumstances:

The average response page is large and you want to reduce the number of round-trips mod_plsql makes to the database to fetch the response.

The character set in use is multi-byte, and you want to compensate for the problem of get_page or get_page_raw fetching fewer bytes for each row (calculations in the OWA Web ToolKit are character-based and in the case of multi-byte characters, OWA packages assume a worst-case character byte size and do not attempt to pack each row to its maximum).

In older versions of the product, this parameter was called response_array_size.

In older versions of the product, the default for this parameter was 128.

PlsqlInfoLogging

Specifies what mode mod_plsql should use to do extra performance logging.

The mode is:

InfoDebug: This logs more information to the Apache's error_log. This is used in conjunction with Apache's "info" logging level. If the Apache's logging level is not at least set to this high, this setting will be ignored.

Category

Value

Syntax

PlsqlInfoLoggingInfoDebug

Default

Empty

Example

PlsqlInfoLogging InfoDebug

This logging setting is useful for debugging problems in your PL/SQL application.

PlsqlMaxRequestsPerSession

Specifies the maximum number of requests a pooled database connection should service before it is closed and re-opened.

Category

Value

Syntax

PlsqlMaxRequestsPerSessionnumber

Default

1000

Example

PlsqlMaxRequestsPerSession 1000

Notes:

This parameter helps relieve memory and resource problems that may occur due to prolonged session reuse by a PL/SQL application.

This parameter should not need to be changed; the default is sufficient in most cases.

Setting this parameter to a low number can degrade performance. A case for a lower value might be an infrequently used DAD whose performance is not a concern, and for which limiting the number of requests provides some benefit.

In older versions of the product, the equivalent to this parameter is reuse. Instead of taking a value of "Yes" or "No", the new parameter enables you to have finer control over the connection pool reuse in mod_plsql.

PlsqlNLSLanguage

Specifies the NLS_LANG variable for this DAD. This parameter overrides the NLS_LANG environment variable. When this parameter is set, the PL/SQL Gateway uses the specified NLS_LANG to connect to the database. Once connected, an alter session command is issued to switch to the specified language and territory. If the middle tier character set matches that of the database, then no alter session call is issued by mod_plsql.

Category

Value

Syntax

PlsqlNLSLanguagestring

Default

None

Example

PlsqlNLSLanguage America_America.UTF8

Notes:

Most applications have PlsqlTransferMode set to CHAR which means that the character set in PlsqlNLSLanguage needs to match the character set of the database. In one special case, where the database and mod_plsql are both using fixed-size character sets, and the character set width matches, the character set can be different. The response character set is always the mod_plsql character set.

If PlsqlTransferMode is set to RAW, then this parameter can be ignored.

In older versions of the product, this parameter was called nls_lang.

PlsqlPathAlias

Specifies a virtual path alias to map to a procedure call. This is application specific.

Category

Value

Syntax

PlsqlPathAliasstring

Default

None

Example

PlsqlPathAlias url

Notes:

For applications that do not use path aliasing,this parameter may be omitted.

In older versions of the product, this parameter was called pathaliasproc.

PlsqlSessionCookieName

Specifies the cookie name whenPlsqlAuthenticationMode is set to SingleSignOn. This parameter is supported only for Oracle Application Server releases, and is used by the Oracle Application Server Portal and Oracle Application Server Single Sign-On.

Category

Value

Syntax

PlsqlSessionCookieNamecookie_name

Default

Same as DAD name

Example

PlsqlSessionCookieName mycookie

Notes:

For DADs not using SingleSignOn authentication, this parameter can be omitted. In most other cases, the session cookie name should be omitted (and this parameter automatically defaults to the DAD name).

A session cookie name must be specified only for Oracle Application Server Portal instances that need to participate in a distributed Oracle Application Server Portal environment. For those Oracle Application Server Portal nodes you want to seamlessly participate as a federated cluster, ensure that the session cookie name for all of the participating nodes is the same.

In older versions of the product, this configuration parameter was called sncookiename.

PlsqlSesssionStateManagement

Specifies how package and session state should be cleaned up at the end of each mod_plsql request.

Setting this parameter to StatelessWithResetPackageState causes mod_plsql to call dbms_session.reset_package_state at the end of each mod_plsql request.

Setting this parameter to StatelessWithPreservePackageState causes mod_plsql to call htp.init at the end of each mod_plsql request. This cleans up the state of session variables in the OWA Web ToolKit. The PL/SQL application is responsible for cleaning up its own session state. Failure to do so causes erratic behavior, in which a request starts recognizing or manipulating state modified in previous requests.

Setting this parameter to StatelessWithFastResetPackageState causes mod_plsql to call dbms_session.modify_package_state(dbms_session.reinitialize) at the end of each mod_plsql request. This API is a lot faster than the mode of StatelessWithResetPackageState, and avoids some latch contention issues, but exists only in database versions 8.1.7.2 and higher. This mode uses up slightly more memory than the default mode.

In older versions of the product, this configuration parameter was called stateful.

An older value of stateful=no or stateful=STATELESS_RESET corresponds to PlsqlSessionStateManagement StatelessWithResetPackageState.

An older value of stateful=STATELESS_FAST_RESET corresponds to PlsqlSessionStateManagement StatelessWithFastResetPackageState.

An older value of stateful=STATELESS_PRESERVE corresponds to PlsqlSessionStateManagement StatelessWithPreservePackageState.

mod_plsql does not support stateful mode of operation. To equip PL/SQL applications with stateful behavior, save state in cookies and/or in the database.

PlsqlTransferMode

Specifies the transfer mode for data from the database back to mod_plsql. Most applications use the default value of CHAR.

Category

Value

Syntax

PlsqlTransferModeCHAR/RAW

Default

CHAR

Example

PlsqlTransferMode CHAR

Notes:

This parameter only needs to be changed to enable sending back responses in different character sets from the same DAD. In such a case, the CHAR mode is useless, since it always converts the response data from the database character set to the mod_plsql character set.

In older versions of the product, RAW transfer mode was not supported.

PlsqlUploadAsLongRaw

Specifies the extensions to be uploaded as LONGRAW data type, as opposed to using the default BLOB data type. The default can be overridden by specifying multi-line directives of file extensions for field. A value of '*' in this field causes all documents to be uploaded as LONGRAW.

Category

Value

Syntax

PlsqlUploadAsLongRawstring multiline

Default

None

Example

PlsqlUploadAsLongRaw jpg, PlsqlUploadAsLongRaw gif

Notes:

For applications that do not do document uploads or downloads, this parameter may be omitted.

PlsqlCacheCleanupTime

Specifies the time to start the cleanup of the cache storage.

This setting defines the exact day and time in which cleanup should occur. The frequency can be set as daily, weekly, and monthly.

To define daily frequency, the keyword "Everyday" is used. The cleanup starts everyday at the time defined. For example, Everyday 2:00. This causes the cleanup to happen everyday at 2 AM (local time) in the morning.

To define weekly frequency, the days of the week such as "Sunday", "Monday", "Tuesday", and so on are used. For example, Wednesday 15:30. This causes the cleanup to happen every Wednesday at 3:30 PM (local time) in the afternoon.

To define monthly frequency, the keyword "Everymonth" is used. The cleanup starts at the Saturday of the month at the time defined. For example, Everymonth 23:00. This causes the cleanup to happen the first Saturday of every month at 11:00 PM (local time) at night.

Category

Value

Syntax

PlsqlCacheCleanupTime<Sunday-Saturday, Everyday, Everymonth> <hh:mm>

Default

Saturday 23:00

Example

PlsqlCacheCleanupTimeSaturday 23:00

PlsqlCacheDirectory

Specifies the directory where cache files are written out by mod_plsql. This directory must exist or else Oracle HTTP Server will not start.

On UNIX, this directory must have write permissions by the owner of the child httpd processes.

Category

Value

Syntax

PlsqlCacheDirectory<directory>

Default

none

Example

PlsqlCacheDirectoryORACLE_HOME/Apache/modplsql/cache

In older versions, this parameter was called "cache_dir" and resides in the "[PLSQL Cache]" section of ORACLE_HOME/Apache/modplsql/cfg/cache.cfg.

PlsqlCacheEnable

Enables mod_plsql caching.

Category

Value

Syntax

PlsqlCacheEnable On/Off

Default

Off

Example

PlsqlCacheEnable On

Notes:

If you are sure that your application does not make use of the OWA_CACHE packages, in the PL/SQL Web Toolkit, then you can choose to disable caching. In such situations, there will be a very minor performance benefit.

In older versions, this parameter is called "enabled" and resided in the "[PLSQL Cache]" section of ORACLE_HOME/Apache/modplsql/cfg/cache.cfg.

PlsqlCacheMaxAge

Specifies the maximum time, in days, a cache file can be allowed to reside in a file system cache, after which the cached file will be removed for cache maintenance.

This setting is to ensure that the cache system does not contain old content. This setting removes old cache files and makes space for new ones.

Category

Value

Syntax

PlsqlCacheMaxAge<number>

Default

30 (30 days)

Example

PlsqlCacheMaxAge 30

PlsqlCacheMaxSize

Specifies the maximum possible size of a cache file.

This setting is to prevent the case in which one file can fill up the entire cache. In general, it is recommended that this be set to about 1-3 percent of the total cache size.

Category

Value

Syntax

PlsqlCacheMaxSize<number>

Default

1048576 (1 MB)

Example

PlsqlCacheMaxSize 1048576

In older versions, this parameter was called "max_size" and resided in the "[PLSQL Cache]" section of ORACLE_HOME/Apache/modplsql/cfg/cache/cfg.

PlsqlCacheTotalSize

Specifies the total size of the cache directory.

This setting limits the amount of space the cache is allowed to use. Both PLSQL cache and Session Cookie cache share this cache space. Note that this setting is not a hard limit. It might exceed the limit temporarily during normal processing. This is normal behavior.

The cleanup algorithm uses this setting to determine how much to reduce the cache files. Therefore, the real space limit is the physical storage's available size.

This parameter takes bytes as values;

1 megabytes = 1048576 bytes

10 megabytes = 10485760 bytes

Category

Value

Syntax

PlsqlCacheTotalSize<number>

Default

20971520 (20 MB)

Example

PlsqlCacheTotalSize 20971520

In older versions, this parameter was called "total_size" and resided in the "[PLSQL Cache]" section of ORACLE_HOME/Apache/modplsql/cfg/cache/cfg.

mod_proxy

mod_rewrite

Oracle HTTP Server provides mod_rewrite as a tool for URL manipulation. A rewriting engine based on a regular-expression parser is used by mod_rewrite to rewrite requested URLs. The granularity of URL manipulations can be affected by the formats of server variables, environment variables, HTTP headers, and time stamps.

This module operates on the full URLs (including the path-info part) both in per-server context (httpd.conf) and per-directory context (.htaccess) and can generate query-string parts on result.

mod_rewrite Rules Processing

Apache processes HTTP in phases. A hook for each of these phases is provided by the Apache API. mod_rewrite uses two of these hooks- the URL-to-filename translation hook which is used after the HTTP request has been read but before any authorization starts, and the Fixup hook which is triggered after the authorization phases and after the per-directory configuration files (.htaccess) have been read, but before the content handler is activated.

mod_rewrite reads the configured rulesets from its configuration structure. Server level rulesets are best configured at startup, while directory level rulesets are configured during the directory access of the kernel.

mod_rewrite loops through the ruleset rule by rule (RewriteRule directive) and when a particular rule matches, it loops through corresponding conditions (RewriteCond directives). First the URL is matched against the Pattern of each rule. When it fails, mod_rewrite looks for corresponding rule conditions. If none are present, it just substitutes the URL with a new value which is constructed from the string Substitution and goes on with its rule-looping. But if conditions exist, it starts an inner loop for processing them in the order that they are listed.

For conditions, a string TestString is created by expanding variables, back-references map lookups, and then CondPattern is matched against the expanded TestString. If the pattern does not match, the complete set of conditions and the corresponding rule fails. If the pattern matches, then the next condition is processed until no more conditions are available. If all conditions match, processing is continued with substituting the URL using Substitution.

When request seeks a URL with more than one slash (/), for example, http://yourserver//oldpath/rqstdrsrc, the "//oldpath" may bypass RewriteCond and RewriteRule directives if they are not correctly written.

For example, consider the following rule:

RewriteRule ^/oldpath(.*) /newpath$1 [R]

Requesting http://yourserver/oldpath/files will redirect and return the page http://yourserver/newpath/files as expected.

However, requesting http://yourserver//oldpath/files will bypass this particular rule, potentially serving a page that you were not expecting it to. You can work around the problem by making sure that rules will capture more than one slash (/). To fix the earlier example, you should use this replacement:

RewriteRule ^/+somepath(.*) /otherpath$1 [R]

mod_rewrite Directives

RewriteEngine

Enables or disables the runtime rewriting engine. If it is set to "Off", this module does no runtime processing at all. Use this directive to disable the module instead of commenting out all the RewriteRule directives.

Rewrite configurations are not inherited by default. This means that you need to have ReWriteEngine On directive for each virtual host in which you want to use it.

RewriteOptions

By specifying RewriteOptions 'inherit', you can force the configuration of the parent by the children. In virtual-server context this means that the maps, conditions and rules of the main server are inherited. In directory context this means that conditions and rules of the .htaccess configuration of the parent directory are inherited.

RewriteLog

Sets the name of the file to which the server logs any rewriting action that it performs. If the name does not begin with a slash (/), then it is assumed to be relative to the Server Root. To disable logging, either remove or comment out the RewriteLog directive or use RewriteLogLevel 0. Avoid setting the filename to /dev/null to prevent logging. This can slow down the server with no advantage.

RewriteLogLevel

Sets the verbosity level of the rewriting log file. The default level 0 means no logging, while 9 or more means that practically all actions are logged.

RewriteBase

Explicitly sets the base URL for pre-directory rewrites. Rewrite rule can be used in per-directory configuration (.htaccess) files. When a substitution occurs for a new URL, the base URL should be added into the server processing. To be able to do this, the module needs to know what the corresponding URL-prefix or URL-base is. By default, this prefix is the corresponding file path itself. However, at most Web sites, URLs are not directly related to physical filename paths. In such cases, you have to use the RewriteBase directives to specify the correct URL-prefix.

If the URLs of your Web server are not directly related to physical file paths, you have to use RewriteBase in every .htaccess files where you want to use RewriteRule directives.

Table 7-5 Rewrite Rules Hints

For example, if you want to redirect requests from /demo1, /demo2, and /demo3 to /alldemos, write the rewrite rule as one of the following:

RewriteRule /demo. /alldemos [R]

or

RewriteRule /demo [123] /alldemos [R]

If you intend that /DemoA, /DemoB, and /DemoC to be redirected to /alldemos, add NC (no case) to the preceding rewrite rules, such as:

RewriteRule /demo [123] /alldemos [R, NC]

This rewrite rule will not work to redirect from /demonstration1 to /demos, because "." works form one character only. To enable redirection of all URLs beginning with "demo", irrespective of subsequent characters, use the rewrite rule as follows:

RewriteRule ^/demo* /alldemos [R, NC]

In the preceding example, ^ means the beginning, * means any character after demo.

If there was a request for /demo1/not_just_index.html, all the preceding rewrite rules would have redirected the request the request to /alldemos/index.html, that may not be what you want. It is quite possible that you may want to redirect to the corresponding files in /alldemos, as listed in Table 7-6.

Table 7-6 Request Redirection

Request for

Redirected to

/demo1/happy.html

/alldemos/happy.html

/demo1/go.jpg

/alldemos/go.jpg

/demos1/lucky.jpg

/alldemos/lucky.jpg

Then you have to use substitution in your rewrite rule as follows:

RewriteRule ^/demos1(.*)$ //alldemos/$1 [R NC]

The explanation for this rule is:

Take the value of the expression, such as happy.html, go.jpg, and lucky.jpg, that appears after demo1 as variables ($1) and substitute it after /alldemos/.

Redirection Examples

For redirecting requests from the DocumentRoot to a directory called newroot, set the following mod_rewrite directives:

RewriteEngine On
RewriteRule ^/(.*)$ /newroot/$1 [R]

For directing requested for files from one directory (olddir) to another (newdir), set the following directives:

RewriteEngine On
RewriteRule ^/olddir(.*)$ /newdir/$1 [R]

In each of these cases, you should ensure that the requested resources are indeed available in the redirected location. The mod_rewrite module does not ensure the existence of the requested resource in the new location.

For disabling all requests using the HTTPTRACE method, set the following mod_rewrite directives: